Heart failure (HF) presents a significant clinical challenge, with current treatments mainly easing symptoms without stopping disease progression. The targeting of calcium (Ca²⁺) regulation is emerging as a key area for innovative HF treatments that could significantly alter disease outcomes and enhance cardiac function. In this review, we aim to explore the implications of altered Ca²⁺ sensitivity, a key determinant of cardiac muscle force, in HF, including its roles during systole and diastole and its association with different HF types—HF with preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). We further highlight the role of the two rate constants k_on (Ca²⁺ binding to Troponin C) and k_off (its dissociation) to fully comprehend how changes in Ca²⁺ sensitivity impact heart function. Additionally, we examine how increased Ca²⁺ sensitivity, while boosting systolic function, also presents diastolic risks, potentially leading to arrhythmias and sudden cardiac death. This suggests that strategies aimed at moderating myofilament Ca²⁺ sensitivity could revolutionize anti-arrhythmic approaches, reshaping the HF treatment landscape. In conclusion, we emphasize the need for precision in therapeutic approaches targeting Ca²⁺ sensitivity and call for comprehensive research into the complex interactions between Ca²⁺ regulation, myofilament sensitivity, and their clinical manifestations in HF.