A　number　of　resources,　every　year,　being　spent　to　tackle　early　detection　of　cardiac　abnormalities　which　is　one　of　the　leading　causes　of　deaths　all　over　the　Globe.　The　challenges　for　healthcare　systems　includes　early　detection,　portability　and　mobility　of　patients.　This　paper　presents　a　categorical　review　of　smartphone-based　systems　that　can　detect　cardiac　abnormalities　by　the　analysis　of　Electrocardiogram　(ECG)　and　Photoplethysmography　(PPG)　and　the　limitation　and　challenges　of　these　system.　The　ECG　based　systems　can　monitor,　record　and　forward　signals　for　analysis　and　an　alarm　can　be　triggered　in　case　of　abnormality,　however　the　limitation　of　smart　phone＇s　processing　capabilities,　lack　of　storage　and　speed　of　network　are　major　challenges.　The　systems　based　on　PPG　signals　are　non-invasive　and　provides　mobility　and　portability.　This　study　aims　to　critically　review　the　existing　systems,　their　limitation,　challenges　and　possible　improvements　to　serve　as　a　reference　for　researchers　and　developers.